Drafting machine



Jan. 18, 1949. EAR. BOOTH 2,459,216

DRAFTING MACHINE Filed May 30, 1945 2 Shets-Sheet l lNvENToR EUST'A'CERUSSELL BOOTH ATTORNEYS Jan. 18, 1949. E, R, BOOTH 2,459,216

DRAFTING MACHINE4 INVENToR EUSTACE RUSSELL'BOOTH BY dEAA/111i, PanmwATTORNEYS Patented Jan. 18, 1949 DRAFTING MACHINE Eustace Russell Booth,Staines, England, assigner of one-half to Sydney Marks, Feltham, EnglandApplication May 30, 1945, Serial No. 596,658 In Great Britain June 6,1944 1 claim. 1

This invention relates to drafting machines and more particularly todrafting machines in which the drawing board is rotatable relatively toits support and is adapted to be locked in various angular positions.The invention has for its object an improved and simplified constructionof drafting machine of this kind. f

In accordance with the invention there is pivoted to the support, whichmay be a pedestal, and which is provided with a socket or a spindle toreceive a spindle, or a socket on the lower side of the drawing board, apair oi pivoted arms provided at their inner ends with toothed quadrantsor the like adapted to mesh and carrying at their outer ends upstandingpins engaging in slots in a straight edge extending across the drawingboard. The straight edge is thus guided parallel to itself over theboard. The drawing board which is suitably provided on its peripherywith angular graduations is tted on its lower side with a disc or platehaving angularly spaced notches or holes corresponding to the angulargraduations on the periphery and adapted to be engaged by aspring-pressed pin supported on the pedestal. The pin is provided with acollar engaged by one end of a lever pivoted on one of the arms, theother end of the lever being located conveniently below and near theedge of the board. The pin is pressed normally by the spring intoengagement with one of these notches or holes and holds the drawingboard locked. To rotate the drawing board to a new angular position itis merely necessary to raise the outer end of the lever in order todepress the pin out of engagement with the notch or hole and when thedrawing board has reached its new position to release the lever when thepin again engages one of the notches or holes on the disc and againholds the drawing board locked.

The invention is illustrated in the accompanying drawing in which Fig. 1is a plan view of the improved drafting machine, Fig. 2 an elevation,Fig. 3 is a detail view of the releasing lever. Fig. 4 is a detailshowing an adjustment for the drawing board and Fig. 5 la detail view ofan auxiliary locking mechanism.

Referring to the drawings, I indicates a circular drawing board which isprovided on its lower side with a tapered spindle 2 to engage a centralsocket on a support which is shown as a spider or tripod 3. Two of thelegs 4 of the spider are provided with bearings 4a to receive pivotmembers 5 by which a pair of arms B are mounted for lateral movement,these arms being provided at their inner ends with toothed quadrants 'Iadapted to mesh. The arms 6 carry at their outer ends upstanding pins 8engaging in slots 9 in a straight edge Ill which is supported by thesepins slightly clear of the surface of the drawing board. Due to themeshing of the quadrants the arms 6 move together and the straight edgeI0 is thus guided parallel to itself over the board. The swing orpivoting of the arms 5 is limited by Pins 'la mounted in sockets in thelegs 4 carrying the arms 6. The pins 'Ia extend through slots 'Ib in therespective webs of the quadrants l. IIhe drawing board is suitablyprovided on its periph eral edge with a metal rim II graduated indegrees and is tted in its lower side with a centrally disposed disc orplate I2 having angularly spaced holes I3 corresponding to the angulargraduations on the periphery and adapted to be engaged by a springpressed pin I4 supported in one of the pivot members 5. The pin I4 isprovided with a collar I5 engaged by one end of a lever I 6 pivoted atI'I on one of the arms G as indicated in Figs. 2 and 3, the other end ofthe lever I6 being located conveniently near the edge of the board. Thepin I4 is pressed normally by means of a spring I8 into engagement withone of the holes I3 and thus holds the drawing board locked. To rotatethe drawing board to a new angular position it is merely necessary toraise the outer end of the lever I6 in order to depress the pin I4 outof engagement with the hole and when the drawing board is rotated to itsnew position to release the lever I6 whereupon the pin engages one ofthe holes in the disc I2 and again holds the drawing board locked.

In order to lock the drawing board in any intermediate position we mayprovide one of the legs 4 with an extension I9, as shown in Fig. 5, towhich is secured a blade spring 20 provided at its outer end with abrake block 2I. The blade spring is engageable by a screw 22. Onrotation of the screw in one direction the brake block is pressedagainst the action of the blade spring 20 against the rim of the drawingboard thus holding it in any desired position. The outer end of theblade spring 20 is inwardly bent as indicated in Fig. 5 to provide apointer pointing to the graduations on the outer rim of the drawingboard.

In order to tilt the board slightly the foot of one of the l-egs 4 ofthe pedestal may be screwthreaded and engaged by a screw 23. By turningthe screw so that it projects beyond the foot, this leg 4, and with itthe drawing board may be tilted.

On the pedestal may be xed an annular rim suitably marked which inconjunction with the to said last-mentioned arm and arranged to'd'e-yrim on the drawing board can be used as a cirpress said pin. i cularslide rule with the straight edg-e employed EUSTACE RUSSELL BOOTH.

as a cursor.

Iclaim; 5 REFERENCES CITED v In a drafting machine, the Combination Witha The following references. are of record inthe drawing board having asupport, of a pair oi outme of mis patent; wardly extending arms pivotedfor lateral move- I ment to the support below the board, each arm UNITEDSTATES PATENTS.' including a toothed quadrant at its inner end 10 NumberName Date beyond its pivot point, the quadrants of the arms 139,507Hitchcock June 3, 1873 being meshed with each other so that the arms434,690 Wardon Aug. 19, 1890 pivot about their pivot pointssimultaneously and 6821061 Bustanoby Dec. 3, 1901 to the same extent, astraight edge mounted over 753,463 Austin' Mar. 1, 1904 the board andconnected tothe outer ends of the 15 837,112 Perkins Nov, 27; 1906 pairof arms at points equdistant from the le- 1,395,200 Moore Oct. 25, 1921spective pivot points of the arms, the `drawing e* 210715331A RonnqujstMar, 15,1937 board being rotatable with respect to the support, aspring-pressed pin carried by said support lat FOREIGN .PATENTS f thepivot point of one of said arms and adapted 20 Number Country Date toengage the drawing board, and a lever pivoted 545,155 Germany Feb. 26,1932

